Power regulator having rapid turn-on circuit

ABSTRACT

The power regulator includes a pass transistor connected between a first supply providing a first unregulated pulsating d.c. voltage and load whose resistance is initially low, but rises to a higher value as power is supplied thereto. An amplifying transistor controls the current flow through the pass transistor and load. A zener diode limits the amplitude of the load voltage. A second supply provides a control voltage to the amplifying transistor which regulates the output power by shaping the output voltage waveform. A starting circuit, connected between a power supply, the load and the amplifying transistor, initially supplies starting current for the regulator. The starting circuit is turned off by the increasing voltage developed across the load as power is delivered thereto.

United States atet [1 1 Del Ciello 1 POWER REGULATOR HAVING RAPID TURN-ON CIRCUIT [76] Inventor: Robert R. Del Ciello, 7809 Cressett Dr., Elmwood Park, 111. 60635 22 Filed: Aug. 19,1971

2| Appl. No.: 173,172

Related U.S. Application Data [63] Continuation-impart of Ser. No. 67,060, Aug. 26,

1970, abandoned.

[52] U.S. Cl 321/18, 315/106, 321/42,

323/22 T, 323/42, 328/262, 328/267 [51] Int. Cl. l-l02m 7/20 [58] Field of Search 323/22 T, 42;

[ Get. 23, 1973 Kemper 323/22 T Webb 323/22 T [57] ABSTRACT The power regulator includes a pass transistor connected between a first supply providing a first unregulated pulsating d.c. voltage and load whose resistance is initially low, but rises to a higher value as power is supplied thereto. An amplifying transistor controls the current flow through the pass transistor and load. A zener diode limits the amplitude of the load voltage. A second supply provides a control voltage to the amplifying transistor which regulates the output power by shaping the output voltage waveform. A starting circuit, connected between a power supply, the load and the amplifying transistor, initially supplies starting current for the regulator. The starting circuit is turned off by the increasing voltage developed across the load as power is delivered thereto.

13 Claims, 5 Drawing Figures PATENTEDUBIZMQH 3.767.997

SHEET 10F 2 E Kit I Q 6' a 33 I94 F I I00 98 J I B lnvenior ROBERT R. DEL CIELLO BY Wa m ATTYS.

PATENTEMBIZEWB 3,767,897

sum 2 0r 2 2 50 IG. fl fii I 58%)56 B A o 2 t TIME t. [2

FIG.

2 C O A 80 8 o V t h '[2 to U IO 203040 50 60 ID 203040 50 60 I020 3040 50 6010 203040 TIME (SECONDS) POWER REGULATOR HAVING RAPID TURN-ON I CIRCUIT CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of application Ser. No.'67,060 filed Aug. 26, l970, now abandoned.

BACKGROUND OF THE INVENTION lt is desirable in some applications to deliver a constant, predetermined amount of electrical power to an electrical load. Electrical power is the rate at which electrical energy is either'generated or absorbed. An example of one such application arises in relation to the heating element or filament included in a vacuum tube such as the cathode ray tube (CRT) utilized either in a television receiver or an oscilloscope. This filament is designed to maintain a cathode located in proximity thereto at a particular optimum operating temperature to facilitate emission of electrons therefrom. The actual operating temperature of the cathode, however, is a function of the quantity of electrical power delivered to the filament. If this quantity of electrical power is either increased or decreased much more than a few percent from the power required to maintain the cathode at its optimum temperature the useful life of the cathode and thus the CRT is substantially decreased. Moreover, the cathode must be brought up to its optimum temperature in as short a time as possible after electrical energy is initially supplied to the filament in order to further maximize the useful life of the CRT.

In the past, a transformer has been uiilized to deliver power to heating elements such as the filaments in vacuum tubes. The primary winding of this transformer is usually coupled to a household type power line delivering a 120 volt, 60 hertz, alternating current (a.c.) voltage, and the secondary winding is usually connected directly across the heating element. Since a transformer is virtually equivalent to a voltage source and since the initial resistance of the heating element is low when the temperature of the element is low, the transformer has a desirable characteristic of rapidly bringing the heating element up to its optimum temperature by rapidly delivering power thereto. (P E /R) However, since the amplitude of the line voltage fluctuates with changes in loading on the associated power distribution system, the amplitude of the secondary winding voltage supplied to the heating element also varies; therefore, the power and consequently the operating temperature of the heating element undesirably fluctuates with changes in line voltage amplitude thereby decreasing the useful life of the cathode.

To solve the foregoing problem, it has been suggested that the well known series voltage regulator, employing a pass transistor, should be connected between the heating element and the voltge supply providing a voltage having a fluctuating amplitude. After the heating element has warmed up, the series voltage regulator supplying a constant amplitude direct current (d.c.) voltage across its terminals does supply a constant amount of power to the heating element. However, until the heating element does warm up this regulator circuit operates unsatisfactorily because it cannot regulate until the amplitude of the voltage across the load or heating element exceeds a particular value. This amplitude, however, depends on the resistance of the heating element which in turn depends on its temperature. Moreover, while the regulator is operating in its unregulated mode the collector of the pass transistor which is connected to the load appears as a constant current source.

Since the output of the collector is limited and the re sistance of the heating element is initially low, the regulator cannot deliver much power to the load until either the temperature of the load increases or the regulator is able to operate in its regulated mode. Therefore, because of the initial low resistance of the heating element, the constant current characteristics of the pass transistor and the inability of the regulator to operate under low amplitude output voltage conditions, the conventional voltage regulator circuit has an undesirably long starting time during which the heating element is not operated at its optimum temperature. Furthermore, the voltage regulator circuit supplying a d.c. output voltage having a constant amplitude is undesirable for use in high production consumer products, such as television receivers, because it requires a plurality of rectifiers and a large expensive filter capacitor.

SUMMARY OF THE INVENTION An object of this invention is to provide a reliable, inexpensive and simple circuit for supplying a predetermined amount of electrical power to a load.

Another object of this invention is to provide a power regulating circuit for rapidly supplying a constant amount of electrical power to a load whose resistance is initially low but rises to a greater value as power is applied thereto.

Still another object of this invention is to provide a power regulator circuit suitable for rapidly supplying energy to the filament of a vacuum tube.

In brief, the power regulator circuit of one embodiment of the invention includes a transformer having two windings, across which out-of-phase, unregulated a.c. voltages are developed. One of these windings delivers an unregulated a.c. input voltage to a half-wave rectifier which develops a first unregulated, pulsating d.c. voltage at its output in response thereto. This voltage is delivered to a pass transistor which is connected in series with a load requiring constant power. An amplifying transistor is connected with the pass transistor so as to control the amplitude of the pulsating d.c. load voltage developed at the outputof the pass transistor. A zener diode provides a first control voltage to the amplifying transistor which limits the maximum amplitude of the load voltage. The other winding of the transformer provides a second control voltage to the amplifying transistor. This control voltage is applied to the control electrode of the amplifying transistor to provide a second pulsating d.c. voltage which is out-ofphase with the first pulsating d.c. voltage from the rectifier. As the second pulsating direct current voltage is applied to the pass transistor, it shapes the waveform of the load voltage to compensate for the undesirable tendency of the power thereof to vary with changes in the amplitude of the unregulated input voltage.

A starting circuit which utilizes the resistance of a heating load may be included in the power regulator. A starting transistor has its output electrode connected to the amplifying transistor, its input electrode connected to the transformer, and its control electrode connected to the load. The starting transistor is initially biased on so as to apply a starting voltage to the amplifying transistor thereby enabling the pass transistor to initially deliver a substantial amount of power to the load. The laod initially has a low resistance which increases according to the amount of power delivered thereto. As the resistacne of the load increases, a voltage is developed thereacross which rises to a threshold level indicating that the voltage thereacross has sufficient amplitude to sustain operation of the regulator. The starting transistor is rendered nonconductive by this level so that it does not interfere with power regulation.

BRIEF DESCRIPTION OF-TI-IE DRAWINGS FIG. 1 is a schematic diagram of a power regulating circuit employing a wave shaping technique; I

FIG. 2 is a schematic diagram of a power regulating circuit employing a wave shaping technique and including a starting circuit;

FIG. 3 includes two families of waveforms. The first family illustrates the variation in amplitude of the unregulated input voltage and the second family shows the corresponding variation in output power;

FIG. 4 includes another set of waveforms showing the wave shaping componsation that maintains the output powers of the regulators of FIGS. 1 and 2 at constant values; and

FIG. 5 includes graphs illustrating the temperature versus time characteristics of the filament of a cathode ray tube connected to a transformer, the circuit of FIG. 1 and the circuit of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT A schematic diagram of power regulating circuit 10 for applying a constant amount of power to a load having a varying resistance is illustrated in FIG. 1. This power regulator may be considered as being comprised of a voltage regulator and a wave shaping circuit. The structure and operation of the voltage regulator will first-be described. Power transformer 11 includes primary winding 12 and secondary winding 14. Input terminals 16 and 18 of primary winding 12 are connected to an alternating current (a.c.) supply'such as a power line supplying 120 volt, 60 hertz household current. The amplitude of the voltage E applied by such supply is subject 'to fluctuation because the voltage drops across the impedance of the power-line and'across'the internal impedance of the generating source vary with changes in the current flowing therethrough caused by variations in the load coupled to the associated power distribution system. 7

Output terminals 20, 22 and 24 are conductively connected to selected points on tapped secondary winding 14. Half-wave rectifying diode 26 is connected from output terminal 20 to the emitter of series pass or regulating transistor 28. The collector of transistor 28 is connected both to the cathode of zener diode 30 and to terminal 32 of electrical load 34 to which it is desired to deliver a constant amount of power.

Load 34 may be the heating element or the filament for the cathode of a vacuum tube such as a cathode ray tube (CRT). The life of such cathodesand other heated elements is a function of the quantity of electrical power delivered thereto. The life of a CRT cathode has been found to be longest when a constant, predetermined quantity of power is delivered to the filament. For instance, the life of a CRT cathode is on the order of 6,000 hours when an optimum quantity of power is delivered to its filament. However, if the filament or heater voltage is decreased by 10 percent with respect to the optimum value, the cathode life is shortened to 1,200 hours, and if the filament voltage isincreased by 10 percent with respect to the optimum value, the life is shortened to 2,500 hours.

The base of transistor 28 is connected through resistor 36 to the collector of amplifying transistor 38, which is of the opposite conductivity type to transistor 28, and through starting resistor 40 to the cathode of zener diode 30. One terminal of the resistive element of potentiometer 42 is connected to the collector of series pass transistor 28. For purposes of explaining the voltage regulator, terminal 43 of potentiometer 42 will be considered as only being connected through dotted conductor 44 to terminal 22 of secondary winding 14,

and not to terminal 24 through conductor 51. The selecting portion of potentiometer 42 is coupled to the base of amplifying transistor 38. The emitter of transis tor 38 is connected to the anode of zener diode 30 and through emitter resistor 45 to terminal 22 of secondary winding 14.

The circuitry thus far described comprises a series voltage regulator of a type known in the art. The operation of this circuit will be described so that the problems overcome by the wave shaping technique of the invention willbe more readily understood. In operation, the unregulated a.c. voltage E is applied to primary winding 12 andzinduces another unregulated a.c. voltage E in the portion of secondary winding 14 between terminals 20 and 22. Diode 26half-wave rectified E thereby forming unregulated pulsating d.c. pulses at the emitter of series pass transistor 28. These pulses forward bias the base-emitter junction of transsistor 28. Starting resistor 40 in combination with potentiometer 42 and load 34 initially provide a path for the base current of transistor 28 thereby allowing it to conduct a small amount of collector current. As this current flows through potentiometer 42, a voltage is developed at the base of amplifying transistor 38 of the required polarity to render it conductive. Since the series circuit of resistor 36-, conducting transistor 38 and emitter resistor 45 forms a lower impedance path leading to terminal 22 than does the path through starting resistor 40, the greater portion of the base current for transistor'28 passes through amplifying transistor 38. Hence, assuming that load '34 has a sufficient resistance, as transistor 38 conducts base current for transistor 28, the potential at the collector of transistor 28, which is also the voltage E across load 34, exceeds the breakover voltage of zener diode 30 thereby allowing the voltage regulator to begin operating in its regulating mode. The situation where load 34 initially has a low resistance will be considered later. The voltage amplitude limiting function of circuit l0.will next be considered.

If the amplitude of E, increases or the impedance of load 34 increases, the amplitude of voltage E, at the collector of series pass transistor 28 attempts to rise, thereby causing the zener breakover potential of zener diode 30 to be exceeded. As a result, zener diode 30 passes an increased quantity of current through emitter resistor 45, thereby developing an increased potentioal thereacross which tends to reverse bias amplifying transistor 38. This operation instantaneously reduces the base current of series pass transistor 28, thereby reducing the collector or load voltage back to its regulated value. On the other hand, if the amplitude of E, decreases or the load impedance decreases, the amplitude of voltage E attempts to, likewise, decrease below the zener breakover potential. As a result, the current through zener diode 30 is decreased and the reverse biasing potential across emitter resistor 45 accordingly decreases thereby increasing the base current, and hence, the collector current of transistor 28. This increase in collector current instantaneously raises the amplitude of output voltage E, to its regulated value. Thus, the amplitude of voltage E at collector 28 remains constant whether the load impedance increases or decreases and whether the amplitude of input voltage E, increases or decreases. The setting of potentioiiieter 42 determines the base bias of transistor 38. The value of the stabilized amplitude of the voltage E therefore, depends on the breakover potential of zener diode 30 and on the setting of the selecting element of potentiometer 42.

Each of the waveforms in FIG. 3A, represents a different amplitude input voltage, E developed across the portion of secondary winding 14 between terminals 20 and 22. Waveform 48 represents an ac. voltage, E having a nominal amplitude; waveform 50 represents an E having a greater than nominal amplitude; and

waveform 52 represents an E having an amplitude less than nominal. Dotted line 54 represents the aforementioned regulated voltage level. In FIG. 3B, waveforms 56, 58 and 60 respectively, illustrate the output at the collector of transistor 28 provided in response to waveforms 48, 50 or 52. Since, the electrical power provided by each of the waveforms in FIG. 3B to load 34 is proportional to the area under each of the associated curves, it is apparent that the output power varies with the amplitude of voltage E even though the amplitude of the load voltage remains constant. Therefore, without corrective wave shaping, the power delivered to load 34 would vary with the change in the amplitude of the input voltage. As previously mentioned, however, it is desired that a constant amount of power be delivered to load 34 even though there are changes in the amplitude of input voltage E,, or the resistance of load The portion of secondary winding 14 connected between terminals 22 and 24 is included in voltage regulator circuit to prevent change in output power with change in input voltage amplitude. Now assume that potentiometer terminal 43 is not connected to secondary terminal 22, through dotted conductor 44, but is connected through conductor 51 to secondary terminal 24. An a.c. wave shaping voltage E is developed across terminals 22 and 24 in response to voltage 15,. Voltage E is 180 out-of-phase with E and its amplitude is proportional to the unregulated amplitude of E Voltage E, is developed across potentiometer 42 and applied to the base of amplifying transistor 38 thereby applying a pulsating dc. current to the base of the transistor 28. The pulsating current resulting from E tends to bias pass transistor 28 so that it selectively resists the current flow therethrough caused by the pulsating current from diode 26. This action results in shaping of E so that a constant amount of power is delivered to load 34 FIG. 2. Waveform 64 illustrates the shaping voltage, E also produced in response to an E, having a nominal amplitude. Waveform 66 shows the shape of the E, produced across load 34 in response to the application of the positive going portion of waveform 48, by the diode 26, and the negative going portion of waveform E to pass transistor 28. The shaping circuit is designed such that the area and thus the energy of waveform 66 contains the optimum amount of power required by load 34.

Similarly FIG. 4B shows a secondary waveform 50, shaping voltage 68 and output voltage 70 produced in response to an input voltage, E, having a greater than nominal amplitude. Although the slopes of sides 72 and 74 of waveform 70 are increased with respect to the corresponding slopes of waveform 66, the depth of dip 76 also is increased thereby causing waveform 70 to include the same area as waveform 66, and, hence, the same power.

Moreover, FIG. 4C shows the secondary waveform 52, shaping voltage 76 and output voltage 78 produced in response to an input voltage, E, having less than nominal amplitude. Although the slopes of sides 80 and 82 of waveform 78 are less than the corresponding slopes of waveform 66, the depth of dip 84 is not as great. Therefore waveform 88 also includes about the same amount of power as waveform 66. Therefore, the area under the E curve and the power contained there remains about the same regardless of changes in amplitude of the line voltage E, or changes in the resistance of load 34.

The circuit as thus far described, operates satisfactorily, if a load having a fixed resistance is connected between terminals 32 and 35; however, if a heating element, having an initially low resistance which rises with temperature, is connected therebetween, the turn-on time is undesirably slow. As the temperature of such elements stabilizes, its resistance likewise stabilizes. To obtain the maximum life from for example, a cathode heated by the element, it is important that the operating temperature of the element be reached as rapidly as possible. If the heating element is connected across a constant voltage source, such as a transformer, the operating temperature is reached in a relatively short time with respect to when the operating temperature is reached if the element is connected to a constant current source. Referring to FIG. 5, curves are shown which represent the temperature versus time characteristic ofa heater element or filament included with a gun in a small portion of the neck of a CRT. This structure is commonly used to study CRT filament and cathode characteristics. Curve 88 illustrates the temperature versus time graph of the filament as it is initially energized by power regulating circuit 10 of FIG. 1. Curve 90, on the other hand, illustrates the temperature versus time characteristic of the same structure with a transformer delivering unregulated power thereto.

Point 92, on curve 90 illustrates that the filament or heater temperature reaches 445 in about 30 seconds with a transformer connected thereto, and point 94 on curve 88 illustrates that it takes about seconds for the filament to reach the same temperature with the regulator circuit 60 of FIG. 1 connected thereto. Therefore, the circuitry 10 of FIG. 1 is about three times as slow as a transformer.

The undesirably long warm up time occasioned by the circuit of FIG. 1 results because the collector of transistor 28 appears as a constant current source which cannot deliver much power to a heating element having a low resistance thereby causing it to warm up slowly while the circuit operates in its unregulated mode. The amplitude of the voltage across load 34 must exceed the breakover potential of zener diode 30 before the'circuit can operate in its regulated mode but it cannot do so until the resistance of load 34 exceeds a certain value. Thus, the regulator remains in its unregulated mode for an excessive amount of time until the heater load warms up. Hence, the foregoing power regulator applies an improper quantity of power to the filament for an undesirable long period of time immediately after initial energization to a filament.

To decrease the amount of'load warm-up or regulator turn-on time, the turn-on circuitry of block 90 of FIG. 2. has been inserted in the power regulator circuit of FIG. 1. The emitter of turn-on transistor 94 is connected to the anode of the zener diode 30 and to the emitter of amplifying transistor 38. The base of transistor 94 is coupled through resistor 96 to terminal 32 of load 34, and through resistor 98 to secondary terminal 24. The collector of transistor 94 is coupled through resistor 100 to terminal 24.

In operation, as the circuit of FIG. 2 is first energized, the temperature and resistance of load 34 has a comparatively low value. Thus, the voltage across load 34 has a low amplitude While E is positive going, the voltage E applied at the base of transistor 94 through resistor 98 is initially negative with respectto the potential at the emitter of transistor94. Hence, turn on transistor 94 is initially forward biased by E during the positive half "cycles of E thereby providing a voltage drop across resistor 45. This voltage drop is positive at end 102 of resistor 45vwhich is connected to terminal 22 of secondary winding 14, and negative at end 104, which is connected to the emitter of transistor 38. Thus the polarity of this potential initially causes amplifying transistor 38 to turn-on thereby rapidly providing a base current path for series pass transistor 28. Therefore, transistor 94 facilitates a much faster turn-on time for the voltage regulator. The greater quantity of available electrical power facilitates a rapid increase in load temperature and resistance. As the resistance of load 34 increases, the amplitude of voltage E thereacross increases untila threshold is reached whereat the forward bias voltage of transistor 94' is overcome and transistor 94 is reverse biased thereby, in effect, disconnecting it from the circuit so that power regulation as previously explained can .occur. Curve 106 of FIG. 5 illustrates the temperature versus time characteristic of the previously mentioned CRT testing structure with the circuit of FIG. 2 supplying power thereto. The shape of curve 106 compares favorably with curve 92, and illustrates that start-up circuit 90 enables the correct operating temperature for the filament of a CRT, for instance, to be reached in a time period on the order of 50 seconds sooner each time the CRT is energized by turning on a television receiver. Hence, startup circuit 90 facilitates a substantial increase in the longevity of the CRT.

Values and designations for components used in a working embodiment of the circuit shown in FIG. 2 for providing approximately 7.7 watts of regulated output power are as follows:

Primary winding 12 above pt. 22 86 turns of No. 21 wire Secondary winding 14 below pt. 22 32 turns of No. 34 wire Diode 26 lN4998 Transistor 28 2N l 76 Zener diode 30 lN4099, 6.8V Load Resistor 34 Heater for CRT 25ZP22 Resistor 36 I00 ohms Transistor 38 2N3903 Resistor 40 680 ohms Potentiometer 42 5 kilohms Resistor 45 180 ohms Transistor 94 2N 3905 Resistor 96 l kilohm Resistor 98 l kilohm Resistor 100 100 ohms Resistors 96 and 98 form a first series circuit and resistor 96, the base-to-collector junction of transistor 94 and resistor 100 form a second series circuit which are, in effect, connected across load resistor 34. As a practical matter, the amount of resistance in each of these series circuits must be relatively large as compared to the value of load resistance 34 so that most of the power developed by the regulator is delivered to the load re.- sistance. This can be accomplished by making the value of resistor 96 large, e.g., l,000 ohms, as compared to the value of load resistor 34, e.g., approximately 5 ohms.

Referring to FIG. 4, it is noted that between times t1 and t2, when series pass transistor 28 is nonconductive, a positive voltage, E3 is developed between points 22 and 24 by transformer 11. Resistors 98 and 96 form a first series path and resistor 100, the base-to-collector junction of transistor 94, and resistor 96 form a second series path by which this voltage is applied across resistor 34. However, since these two series paths offer a high resistance to the voltage as compared to load resistance 34, little power is supplied to the load resistor be tween times t1 and t2. Thus, the variations in amplitude of the portion of voltage E3, occurring between times t1 and t2 provides virtually no change in the amount of electrical power delivered to the load. Additionally, between times t0 and t1, when series pass transistor 28 is conductive, the negative portion of voltage E3 in effect controls transistor 28 through transistor 38 and thereby has a substantial effect on the voltage E, developed across the load. i

For instance, under one set of operating conditions the load voltage regulated level 54 of FIG. 3 was set at 6.3 volts. Between times t0 and tl,E3'has an amplitude which caused the depth of the dip 76 in the load voltage to be on the order of 2 volts but the amplitude of the load voltage caused by signal E3 between times t1 and t2 was measured to be less than 40 millivolts. Thus, even if the line voltage amplitude should vary as much as 25 percent, the resulting change in voltage across the load by the change in voltage E3 between times t] and t2 could only be on the order of 10 millivolts. Therefore, the circuit of FIG. 2 is suitable for supplying virutally constant power to a load notwithstanding the change in amplitude of voltage E3 caused by line voltage changes between times tl and t2 provided that the series combination of resistors 100 and 96, and the series combination of resistors 100 and 96, and the series combination of resistors 98 and 96 each have a large value as compared to load resistor 34.

What has been described, therefore, is a simple and inexpensive circuit for applying a predetermined, regulated amount of power to an electrical load. This power regulator circuit includes a turn-on circuit for enabling an electrical load in the form of a heater for a vacuum tube to rapidly be brought up to its optimum temperature. Moreover, the circuit includes no bulky, expensive filter capacitors.

I claim:

1. A power regulating circuit for applying a constant predetermined quantity of electrical power to a load, said power regulating circuit including in combination:

first voltage supply means providing a first alternating current voltage having an amplitude which is subject to variation;

rectifying means connected to said first voltage supply means and providing a first pulsating direct curient voltage at its output terminal having an amplitude subject to undesirable variation with said variation in amplitude of said first alternating current voltage;

first electron control means having first input; control and output electrodes, said first input electrode being connected to said output terminal of said rectifying means, said first output electrode being connected to the load;

second electron control means having second input,

control and output electrodes, said second output electrode being coupled to said first control electrode;

third electron control means having a zener characteristic coupled with said output electrode of said first electron control means and applying a reference voltage to said control electrode of said first electron control means which controls the amplitude of the voltage across said load;

second voltage supply means providing a second alternating current voltage which has an amplitude that varies with said amplitude of said first alternating current voltage, and which is 180 out-of-phase with said first alternating current voltage;

first circuit means applying said second alternating current voltage to the input electrode of siad second electron control means, said second electron control means producing a second pulsating direct current voltage at the control electrode of said first electron control means having an amplitude which varies in synchronism with said variation in amplitude of said first pulsating direct current; and

said first electron control means responding to said reference voltage and said first and second pulsating direct current voltages to provide a third pulsating direct current voltage transferring the predetermined quantity of electrical power to the load.

2. The power regulating circuit of cliam 1 wherein said first and second voltage supply means are portions of the secondary winding of a transformer having its primary winding coupled to a supply of alternating current voltage the amplitude of which is subject to variation.

3. The power regulating circuit of claim 1 wherein said third electron control means is a zener diode connected from said first output electrode to said second input electrode.

4. The power regulating circuit of claim 1 wherein said load includes a heater for the cathode of a vacuum tube.

5. The power regulating circuit of claim 1 wherein said rectifying means is a semi-conductor diode, said first electron control means is a transistor of one coductivity type, and said second electron control means is a transistor of conductivity type opposite to said one conductivity type of said first electron control means.

6. The power regulating circuit of claim 1 further including a potentiometer having a resistive element with first and second terminals and a selecting portion with a third terminal, said first terminal of said potentiom' eter being coupled to said first output electrode, said second terminal of said potentiometer being coupled to said second voltage supply means, said third terminal of said potentiometer being coupled to said second control electrode, said potentiometer applying said second alternating current voltage to said second electron control device which provides said second pulsating direct current voltage to said first control electrode in response thereto.

7. A power regulator circuit for rapidly applying power to a load that initially has a low resistance which increases after power is applied thereto; such power regulator circuit including in combination:

voltage supply means providing unregulated voltage on first and second output terminals;

first electron control means having first input, control and output electrodes, said first input electrode being coupled to the first terminal said voltage supply means and said first output electrode being coupled to the load;

second electron control device having second input,

control and output electrodes, said second output electrode being coupled to said first control electrode, said second electron control device having a conductivity which varies according to the polarity and amplitude of the voltage applied between said second control and input electrodes;

starting electron control device having third input,

control and output electrodes, said third control electrode being coupled to the load, said third input electrode being coupled to the second terminal of said voltage supply means, said third output electrode being coupled to said second input electrode; and,

bias means connected to said starting electron control device which initially biases it on thereby providing starting current which renders said second electron control device and said first electron control device conductive thus causing a substantial amount of power to be rapidly supplied to the load, said starting electron control device being biased off as the voltage across said load rises to a preselected amplitude.

8. The power regulating circuit of claim 7 wherein said voltage supply means provides first and second out-of-phase unregulated voltages at said first and second output terminals thereof, said first electron control device having said first input electrode thereof connected to said first output terminal of said voltage supply means;

said starting electron control device having said third input electrode thereof connected to said second output terminal of said voltage supply means thus providing said starting current.

9. The power regulating circuit of claim 7 further including zener diode means connected from said first output electrode to said second input electrode and first resistive means connected from said second input electrode to a reference potential, said zener diode conducting a control current to said first resistive means which controls said voltage between said second control and input electrodes by varying the voltage across said first resistive means thereby limiting the amplitude of said voltage applied across the load.

10. The regulator of claim 9 wherein a second resistive means is connected from said first control electrode of said zener diode means to facilitate initial conduction of said first electron control device.

ll. The power regulator of claim 8 further including a potentiometer having a resistive element with first and second terminals and a selecting portion with a third terminal, said first terminal being coupled to said first output electrode, said second terminal being coupled to said second terminal of said voltage supply means, said selecting portion being coupled to said second control electrode, said potentiometer providing a the load is a heater for the cathode of a vacuum tube.

fil 

1. A power regulating circuit for applying a constant predetermined quantity of electrical power to a load, said power regulating circuit including in combination: first voltage supply means providing a first alternating current voltage having an amplitude which is subject to variation; rectifying means connected to said first voltage supply means and providing a first pulsating direct current voltage at its output terminal having an amplitude subject to undesirable variation with said variation in amplitude of said first alternating current voltage; first electron control means having first input; control and output electrodes, said first input electrode being connected to said output terminal of said rectifying means, said first output electrode being connected to the load; second electron control means having second input, control and output electrodes, said second output electrode being coupled to said first control electrode; third electron control means having a zener characteristic coupled with said output electrode of said first electron control means and applying a reference voltage to said control electrode of said first electron control means which controls the amplitude of the voltage across said load; second voltage supply means providing a second alternating current voltage which has an amplitude that varies with said amplitude of said first alternating current voltage, and which is 180* out-of-phase with said first alternating current voltage; first circuit means applying said second alternating current voltage to the input electrode of siad second electron control means, said second electron control means producing a second pulsating direct current voltage at the control electrode of said first electron control means having an amplitude which varies in synchronism with said variation in amplitude of said first pulsating direct current; and said first electron control means responding to said reference voltage and said first and second pulsating direct current voltages to provide a third puLsating direct current voltage transferring the predetermined quantity of electrical power to the load.
 2. The power regulating circuit of claim 1 wherein said first and second voltage supply means are portions of the secondary winding of a transformer having its primary winding coupled to a supply of alternating current voltage the amplitude of which is subject to variation.
 3. The power regulating circuit of claim 1 wherein said third electron control means is a zener diode connected from said first output electrode to said second input electrode.
 4. The power regulating circuit of claim 1 wherein said load includes a heater for the cathode of a vacuum tube.
 5. The power regulating circuit of claim 1 wherein said rectifying means is a semi-conductor diode, said first electron control means is a transistor of one conductivity type, and said second electron control means is a transistor of conductivity type opposite to said one conductivity type of said first electron control means.
 6. The power regulating circuit of claim 1 further including a potentiometer having a resistive element with first and second terminals and a selecting portion with a third terminal, said first terminal of said potentiometer being coupled to said first output electrode, said second terminal of said potentiometer being coupled to said second voltage supply means, said third terminal of said potentiometer being coupled to said second control electrode, said potentiometer applying said second alternating current voltage to said second electron control device which provides said second pulsating direct current voltage to said first control electrode in response thereto.
 7. A power regulator circuit for rapidly applying power to a load that initially has a low resistance which increases after power is applied thereto; such power regulator circuit including in combination: voltage supply means providing unregulated voltage on first and second output terminals; first electron control means having first input, control and output electrodes, said first input electrode being coupled to the first terminal said voltage supply means and said first output electrode being coupled to the load; second electron control device having second input, control and output electrodes, said second output electrode being coupled to said first control electrode, said second electron control device having a conductivity which varies according to the polarity and amplitude of the voltage applied between said second control and input electrodes; starting electron control device having third input, control and output electrodes, said third control electrode being coupled to the load, said third input electrode being coupled to the second terminal of said voltage supply means, said third output electrode being coupled to said second input electrode; and, bias means connected to said starting electron control device which initially biases it on thereby providing starting current which renders said second electron control device and said first electron control device conductive thus causing a substantial amount of power to be rapidly supplied to the load, said starting electron control device being biased off as the voltage across said load rises to a preselected amplitude.
 8. The power regulating circuit of claim 7 wherein said voltage supply means provides first and second out-of-phase unregulated voltages at said first and second output terminals thereof, said first electron control device having said first input electrode thereof connected to said first output terminal of said voltage supply means; said starting electron control device having said third input electrode thereof connected to said second output terminal of said voltage supply means thus providing said starting current.
 9. The power regulating circuit of claim 7 further including zener diode means connected from said first output electrode to said second input electrode and first resistive means coNnected from said second input electrode to a reference potential, said zener diode conducting a control current to said first resistive means which controls said voltage between said second control and input electrodes by varying the voltage across said first resistive means thereby limiting the amplitude of said voltage applied across the load.
 10. The regulator of claim 9 wherein a second resistive means is connected from said first control electrode of said zener diode means to facilitate initial conduction of said first electron control device.
 11. The power regulator of claim 8 further including a potentiometer having a resistive element with first and second terminals and a selecting portion with a third terminal, said first terminal being coupled to said first output electrode, said second terminal being coupled to said second terminal of said voltage supply means, said selecting portion being coupled to said second control electrode, said potentiometer providing a path for said second alternating voltage to said second electron control device to thereby vary the voltage applied to said first control electrode such that the power delivered to the load remains constant even though said output voltage of said voltage supply means varies in amplitude.
 12. The power regulating circuit of claim 8 wherein said voltage supply means is a power transformer having primary and secondary windings and said first and second output terminals are taps on the said second winding.
 13. The power regulating circuit of claim 7 wherein the load is a heater for the cathode of a vacuum tube. 